This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are proposing cutting-edge structural studies that are broadly relevant to vascular biology and immune deficiency. We will pursue crystallographic investigations on prostacyclin (PS) and thromboxane synthases (TS) to better understand how vasodilator and vasoconstrictor biosynthesis is mediated in vascular endothelial cells. This study is also important for gaining a better understanding of how drugs like Vioxx[unreadable] and Celebrex[unreadable] diminish prostacyclin production. Furthermore PS is a target for minoxidil ? the active ingredient of Rogaine[unreadable]. We also plan to combine the structural information obtained from our studies on PS and TS with allene oxide synthase (AOS) to provide a holistic view of how heme proteins utilize endo- and hydroperoxide substrates. Furthermore, by interrogating the structure of CYP8B1 ?sterol 12alpha hydroxylase? we will be able to provide a molecular basis for how novel functions evolve from preexisting cytochromes P450 templates and also gain insights into gallstone formation. On the immunodeficiency front we will determine the structure of activation-induced deaminase (AID), its complexes with DNA and other proteins. We will also probe chemokine receptors that belong to the G-protein couple receptor superfamily.